The invention relates to connecting a die in an integrated circuit module.
In a multi-chip module (MCM), a number of integrated circuit dies and associated discrete chips are placed on a single interconnecting substrate. In this manner, very high pin counts can be achieved internally on the MCM interconnecting substrate, with the MCM package providing fewer output pins than are found internally.
A number of techniques exist to attach the dies to the substrate in an MCM device, including wire bonds, flip chip solder bumps, tape automated bonding leads, and micro-bump bonds. The entire assembly is then packaged using packaging techniques common to single chip modules.
Multi-chip modules can also be fabricated using packages that contain sockets having channels or slots configured to receive bare dies, such as the multi-chip module connector disclosed in U.S. Pat. No. 5,104,3249. Such multi-chip modules are referred to as direct die contact (DDC) modules. The sockets in the DDC modules allow the bare dies to be mounted perpendicularly with respect to the interconnecting substrate of the module, thereby achieving higher device density in an MCM. Spring arms are provided in each socket to electrically contact corresponding bond pads of the die inserted into the socket. The spring arms are aligned with respect to the die bond pads in each socket.
With improvement in process technology, die sizes are steadily being reduced. Due to the smaller die sizes, the overall size of the bond pads on each die and the pitch between bond pads are proportionately reduced. This may affect the alignment of the die bond pads to spring arms in the socket of a DDC multi-chip module.
Generally, the invention is directed to a socket that receives a bare die and provides contacts of varying lengths to align properly to bond pads on the die, the bond pads arranged such that they are displaced with respect to one another along one particular direction.
Among the advantages of the invention is that reliable contacts can be made with bond pads of a reduced size die inserted into a direct die contact socket. Accurate alignment of the contacts in the socket to the die bond pads can be achieved. On smaller dies in which bond pads are densely populated, the contacts of the sockets can properly align to the corresponding bond pads while still satisfying minimum pitch requirements between contacts. Further, the alignment is tolerant of variations of die sizes (such as due to variances in wafer cutting) that can cause the position of a die to be shifted in the socket.
In general, in one aspect, the invention features an integrated circuit module that includes a die having bond pads in a socket adapted to receive the die. Contacts having varying lengths are disposed in the socket to electrically contact the bond pads on the die.
In general, in another aspect, the invention features a chip-carrying module including a socket for receiving a die having first and second sets of bond pads. A first contact having a first length is disposed in a socket for electrically contacting the first set of bond pads on the die, and a second contact having a second length is disposed in the socket for electrically contacting to a second set of bond pads on the die. The first length is different from the second length.
In general, in another aspect, the invention features a semiconductor module having a die with bond pads that are displaced with respect to one another along a particular direction. A socket is configured to receive the die, the socket having contacts for electrically contacting the die.
In general, in another aspect, the invention features a method of creating an integrated circuit module. Bond pads are formed on a die that are displaced with respect to one another along a particular direction. Contacts are formed in a socket. The die is inserted into the socket, the contacts being arranged to contact bond pads upon insertion.
In general, in another aspect, the invention features an apparatus for forming electrical connections to bond pads on a die. The apparatus includes a socket for receiving the die, and contacts are formed inside the socket to contact the bond pads. The contacts have varying lengths.
Other features and advantages will become apparent from the following description and from the claims.